1. Field of the Invention
This invention relates to fabrics and has particular reference to knitted fabric panels. It has further particular reference to knitted fabric panels intended for use in upholstered structures.
2. Description of Related Art
Proposals have been made, see UK patent application no. 2,223,034A, to produce upholstered structures such as upholstered three-dimensional car seats by knitting the entire fabric seat in one operation. This is a radical departure from conventional processes for making upholstered fabric structures wherein the fabric is manufactured by weaving. The woven structure is then cut into shapes and the shapes are stitched together.
The manufacture of upholstered structures by the use of woven fabric requires a number of distinct stages. First of all the yarn has to be formed into a warp and then the warp is transferred to a loom for weaving the fabric. The fabric will inevitably be in rectangular shape. The fabric is then cut into pieces and the pieces are sewn together to form the upholstered fabric for the upholstered structure. At each stage in the operation there are losses in yarn yield -- the warp threads must be continuous and therefore there are losses associated with manufacturing the warp. The weaving operation involves further yarn loss and fabric is lost during the cutting operation. All told the total yield of yarn in the upholstered fabric compared to yarn in the bobbin state is no more than about 60% in the case of a vehicle seat. By knitting the upholstery fabric the yarn yields can be in the upper nineties percent. Furthermore, the knitting operation is a single operation requiring less manual input and less skill once the knitting machine has been set up.
In many cases, however, it is necessary to sew onto the knitted fabric of the upholstered structure. This is either because two knitted components have to be sewn together as it is not possible to knit the entire structure in one operation, or a knitted component has to be joined to a woven component.
British patent specification no. 1,276,185 describes the use of a thermoplastic resin filament which can be heated prior to knitting and becomes deformed during knitting. After knitting the entire structure becomes rigid once more.
British patent specification no. 1,214,939 describes a method of preventing the edge of a knitted fabric from unravelling by incorporating shrinking and adhering yarns in the edges.
U.S. Pat. No. 4,755,242 describes a knitted article such as a glove which incorporates a head shrunk multiple plastic yarn along the edge to prevent the edge unravelling.
Japanese Abstract No. 602755 further describes a trimmed edge fabric particularly for use in glove manufacture in which there is provided a shrinkable yarn at the free edge which is shrunk by heating.
British patent specification no. 2,223,034 describes the incorporation of a fusible yarn at the edge of a hem to prevent unravelling.
British patent specification no. 2,168,607 describes three dimensional trim cover assemblies but does not address the problems of sewing together such assemblies.
British patent specification no. 1,308,909 describes the formation of garment panels incorporating start-up courses into which are knitted elastomeric yarns shrunk on subsequent treatment. Such courses are, however, only set up courses for single jersey whole garment parts.
British patent specification no. 1,033,144 describes knitted fabrics for garments such as sweaters in which there is a stabilised free edge which is intended to be stable in the free condition.
European patent specification no. 361,854 describes the use of knitted joins in upholstery fabrics.